The present invention relates generally to self-retaining smooth bore inserts. More particularly, the present invention relates generally to devices for securely mounting an in-line fluid system component within a smooth bore.
Small bore fluid components such as filters or pressure indicators are frequently required for zero-defect hydraulic control applications. There are numerous applications in the aerospace technologies wherein it is desirable to mount miniature components in small diameter smooth bores of fluid control systems. The dimensional constraints, e.g. bore diameters, typically on the order of 0.25 inch or less, and the environmental operational constraints impose demanding design parameters for the means whereby the fluid components or elements are mounted in the systems.
In U.S. patent application No. 846,961, filed on April 1, 1986 and entitled "Self-Retaining Smooth Bore Insert and Method of Installing Same" of Leighton Lee II and Robert J. Kolp, the inventors herein, a smooth bore insert comprises a self-retaining member which employs a helical spring. One end of the helical coil spring is connected in a fixed manner to the fluid system component. In a relaxed state, the coil spring has an outer diameter which is greater than the predetermined diameter of the smooth bore. The spring frictionally locks the insert within the bore. The ends of the coil spring are relatively rotatable to contract the coil spring slightly by rotation of one end of the spring in one angular direction in relation to the other as a result of frictional resistance between the coil spring and the smooth bore. A connector is threaded to the insert and connects with the helical coil spring. A threaded tool mates with the connector, and upon rotation of the tool, the diameter of the helical coil spring is sufficiently retracted to permit installation of the insert into the smooth bore. Upon counter-rotation of the tool, the helical spring is released to its relaxed state wherein it engages the surrounding wall of the smooth bore to thereby self-retain the insert in position.